1. Field of the Invention
The invention relates to a lighting equipment on a sewing machine, comprising an arm with a bottom side and with a needle bar; and a work area which is allocated to the needle bar and substantially shadowlessly illuminated.
2. Background Art
In a lighting system known from U.S. Pat. No. 6,168,284 B1, a light is provided on the lower side of the sewing machine arm, illuminating the needle bar and a presser foot rod by a coverage greater than 180xc2x0. The light may be a cathode fluorescence lamp. Drawbacks reside in that the glass bulb of the lamp is susceptible to impacts and that lights of this type need a comparatively high operating voltage of 80 V and a high sparking voltage exceeding 300 V. This requires special safety precautions. The current supply equipment is comparatively complicated and costly. The light itself needs a special design, which is accompanied with a high production cost. Obtaining spare parts is complicated. Voltage fluctuations occasion changes in light intensity. Furthermore, a reflector is needed.
DE 87 03 621 U1 describes a lamp, in which the light is led by light guides from a source to the stitch forming area i.e., into the proximity of the needle. Drawbacks reside in the restricted illumination of the stitch forming area, which results in shadows being cast. The light guide itself may interfere with an operator""s sewing job. Light intensities fluctuate upon voltage fluctuations. Mounting requirements are considerable, which is also true for the lamp itself.
It is an object of the invention to develop a lighting equipment of the generic type such that uniform and shadowless illumination of the work area is accompanied with high operational safety, low power consumption, little heat build-up and a low manufacturing cost.
According to the invention, this object is attained by the needle bar being at least bilaterally surrounded by several light emitting diodes which are disposed in at least one lighting device. It is possible to arrange the numerous, approximately spotwise light emitting diodes at the most favorable respective places for optimal shadowless illumination of the work area. Light emitting diodes of this type are characterized by strength and extraordinarily low power consumption i.e., they develop nearly no heat. Several LEDs may be connected in series, with current being fed to any such group of LEDs by their proper stabilized power supply.
Details of the invention will become apparent from the ensuing description of an exemplary embodiment, taken in conjunction with the drawing.